Self made and gate

Lol, sure- it works. But it isn't a good example one should post as a working model. I noticed that instead of using a series resistor you adjusted the LED voltage to the voltage you observed at the output. I'm assuming that at first, the LED was at it's default value (2V,20mA) and when you started the simulation you were surprised to see around 140mA surging through that poor LED. Probably thought to yourself, "damn, I copied it just like the book shows- why isn't it working?". So you did the only thing you could think of and changed the LED's voltage value. Bingo- 20mA! Right? Not exactly. You did see a problem, and I'll give you a couple points for finding your own solution- however this will not work on a real life build. Just think if some beginner saw your "working" example and decided they should try it on a breadboard, but they didn't notice the LED's adjusted voltage. At best, they burn out an LED. Worst case scenario- I dunno, maybe some hot plastic shrapnel in their eyeball. My point being: it's ok if you're still learning and you don't have all the answers, there are people here who will help. Just be careful with what you publish to be authentic and working because a simulation is one thing, but in real life electricity isn't something to be carelessly played with!..

Oh yeah, so let's fix it! All you have to do is place a resistor in series from the output node to the (default) LED. 100 ohms should be good ;^)

Sine you saved my eyes I love you! Lol

91.6 ohm for precision.

I do what I can my friend, I do what I can. Hey @OC- I like this new guy uh, @controlledburn or somethin. He's got a good sense of humor- 91.6 ohm lol, I love it! Hey I just heard- radio shack has a special one day sale- you guessed it they got 91.6 ohm resistors on sale for 46.238% off retail price! Hey I gotta run, I should get down there before they sell out! AAAaahhhaaahahahaa...

He also jacked up the reverse beta of the BJTs all the way, which won't really affect this circuit's operation, but I guess that's kind of the point.

Well, given that 91R is a (somewhat) standard resistance, and that it's probably going to be a 5% tolerance, if you go through enough of them, you'll eventually find one that's 91.6R. ;) Can't find a 91R? Grab a 10R and an 82R, instead. They're both more common. Of course, you could just not be a tard, use a 100R, and be done with it.

Lol yes @rk, just like I said- 100 ohms and call it good..